Computer system administrators and users often are concerned with their computer system's general performance rather than specific details. Users have trouble interpreting the information when presented with a dozen different power ratings, temperatures, fan speeds, etc. Users often want a single number that can be monitored, often over time, to determine if their computer system is in need of attention. In a computer system, one such “number” is the ambient temperature value.
Blade servers are common forms of a computer system. Blade servers include enclosures to house one or more processor blades, storage blades, or other components. Operating the blade server can generate significant amounts of heat. Thus, blade enclosures and the components included therein frequently have associated a thermal management system. This thermal management system may employ many different temperature sensors. Further, different modules may report temperatures in different ways. Some sensors report temperatures in degrees Fahrenheit, others in degrees Celsius, and others may report relative temperatures, for example: “cool,” “warm,” “hot,” or “critical.”
Blade enclosures do not have an ambient temperature sensors built into the enclosure. This is because ambient temperature is too vague to have actual application in thermal management of the enclosure. Accurate thermal management requires precise measurements at critical locations within the enclosure and its modules.
Further, placing an enclosure ambient temperature sensor in a convenient location raises a number of problems. For instance, placing a temperature sensor on one of the enclosure's backplanes may seem an obvious choice. The backplanes contain power and communications capabilities and would not requiring additional cabling or mounting options for the sensor. The problem with this location is that backplanes are located behind the blades, which are significant sources of heat. This location choice would cause a backplane mounted ambient temperature sensor to read much higher than the actual enclosure ambient temperature.
To report an ambient temperature to the user, the ambient temperature must be computed from other sensors in the enclosure. Averaging temperatures of all sensors could possibly mask hot-spots in the enclosure and therefore is not a desirable method of computing an ambient temperature.
In current blade enclosures, ambient temperature often is reported as the temperature sensed in an administrator module. The administrator module in these previous enclosures often is located at the rear of the enclosure, where air flowing over the sensor is pre-heated by the blades located at the front of the enclosure. This results in ambient temperatures being reported that are higher than the enclosure's actual ambient temperature.